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#768840 (Received by flhurricane at: 4:43 PM 09.May.2015) TCDAT1 TROPICAL STORM ANA DISCUSSION NUMBER 8 NWS NATIONAL HURRICANE CENTER MIAMI FL AL012015 500 PM EDT SAT MAY 09 2015 Ana continues to maintain deep convection near and east of the center, although the convection is rather ragged-looking. There is weak upper-level outflow over the southern portion of the circulation. The current intensity is held at 50 kt, in agreement with data from an ASCAT overpass from several hours ago. Since the storm will be moving over progressively cooler waters as it departs the Gulf Stream, and is being influenced by northwesterly shear and some dry air, gradual weakening is forecast until landfall. After Ana crosses the coast, the weakening will of course be more rapid. The official intensity forecast is again close to IVCN, the intensity model consensus. Global model guidance indicates that Ana or its post-tropical remnant will become absorbed by, or merge with, a large extratropical cyclone over Atlantic Canada within 72 hours. The center is a little difficult to locate, but my best estimate of the initial motion is 320/3. The track forecast philosophy continues unchanged. The persistent mid-tropospheric blocking ridge to the north of Ana is predicted by the global models to shift eastward and weaken during the next day or so. The models also depict a broad trough moving eastward from the central to the eastern U.S. over the next 2-3 days. This evolution of the steering currents should cause Ana to turn northward and northeastward. The official track forecast is similar to the dynamical model consensus, IVCN, but leans a little more toward the latest ECMWF solution. FORECAST POSITIONS AND MAX WINDS INIT 09/2100Z 32.9N 78.3W 50 KT 60 MPH 12H 10/0600Z 33.4N 78.6W 45 KT 50 MPH 24H 10/1800Z 34.2N 78.7W 35 KT 40 MPH...INLAND 36H 11/0600Z 35.2N 78.1W 30 KT 35 MPH...INLAND 48H 11/1800Z 36.7N 76.5W 30 KT 35 MPH...INLAND 72H 12/1800Z...ABSORBED $$ Forecaster Pasch |